This invention relates to an air-conditioning system for controlling the temperature and humidity conditions in an air-conditioned area.
The invention more particularly relates to an air-conditioning system of the type in which air is directed through a spray chamber and into direct contact with a spray of water for cooling and conditioning the air and the thus cooled and conditioned air is then supplied to the air-conditioned area. This type of air-conditioning system, sometimes referred to as an "air washer" system, is used most often in industrial applications where both the temperature and the humidity of the air in the air-conditioned area must be controlled within fairly close limits.
It should be understood that in such industrial applications, because of the heat load from the industrial equipment, lighting, and inhabitants as well from the roof and walls of the building, cooling is generally required year-round. The temperature and humidity conditions within the building are controlled by withdrawing air from the building and circulating it through an air-conditioning unit where cooling and/or reheating of the air is carried out as necessary to provide the desired temperature and humidity conditions. A portion of the air may be replaced with fresh outside air prior to the cooled and conditioned air being returned from the air-conditioning unit to the building.
In perhaps the most well-known type of air washer air-conditioning system, the spray of water cools the air to or near the saturation point in order to attain the level of moisture needed to provide the desired relative humidity at the final temperature, and the air is then reheated to bring it to the final temperature with the desired relative humidity level. This approach is particularly well suited for accurately controlling both the temperature and the relative humidity of the air, but is inefficient since energy is required both for initially cooling the air and then for reheating it to the desired final temperature and relative humidity.
In an effort to conserve energy, other known systems have been produced wherein a portion of the air is directed to bypass the spray chamber in order to minimize or avoid the need for subsequent reheating of the air. However, the energy requirements for this type of system are still quite substantial.
In still another type of air washer air-conditioning system, described in U.S. Pat. No. 4,089,666, issued May 16, 1978, efforts were made to further reduce energy requirements by varying the volume of the spray water used for cooling the air in response to variations in the temperature in the air-conditioned area. While this approach provided improvements in energy efficiency over the prior systems noted above, the need still exists for further reducing and conserving energy usage.